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PHP Object Iteration
Introduction
From PHP 5 onwards, it is possible to iterate through list of all visible items of an object. Iteration can be performed using foreach loop as well as iterator interface. There is also IteratorAggregate interface in PHP, that can be used for this purpose
Using foreach loop
Example
<?php
class myclass{
private $var;
protected $var1;
public $x, $y, $z;
public function __construct(){
$this->var="private variable";
$this->var1=TRUE;
$this->x=100;
$this->y=200;
$this->z=300;
}
public function iterate(){
foreach ($this as $key => $value) {
print "$key => $value
";
}
}
}
$obj = new myclass();
foreach($obj as $key => $value) {
print "$key => $value
";
}
echo "
";
$obj->iterate();
?>Output
The output is as below −
x => 100 y => 200 z => 300 var => private variable var1 => 1 x => 100 y => 200 z => 300
Using Iterator Interface
This interfce defines following abstract methods whih will be implemnted in following example
abstract public current ( void ) : mixed abstract public key ( void ) : scalar abstract public next ( void ) : void abstract public rewind ( void ) : void abstract public valid ( void ) : bool
Iterator::current — Return the current element
Iterator::key — Return the key of the current element
Iterator::next — Move forward to next element
Iterator::rewind — Rewind the Iterator to the first element
Iterator::valid — Checks if current position is valid
Following example demonstrates object iteration by implementing Iterator interface
Example
<?php
class myclass implements Iterator{
private $arr = array('a','b','c');
public function rewind(){
echo "rewinding
";
reset($this->arr);
}
public function current(){
$var = current($this->arr);
echo "current: $var
";
return $var;
}
public function key() {
$var = key($this->arr);
echo "key: $var
";
return $var;
}
public function next() {
$var = next($this->arr);
echo "next: $var
";
return $var;
}
public function valid(){
$key = key($this->arr);
$var = ($key !== NULL && $key !== FALSE);
echo "valid: $var
";
return $var;
}
}
$obj = new myclass();
foreach ($obj as $k => $v) {
print "$k: $v
";
}
?>Output
Above code produces following result −
rewinding valid: 1 current: a key: 0 0: a next: b valid: 1 current: b key: 1 1: b next: c valid: 1 current: c key: 2 2: c next: valid:
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